Actuator



ct. 30, 1945. R W, LELAND ETAL 2,387

i ACTUATOR Filed July 19, 1944 5 Sheets-Sheet 1 oci. 3o, 1945. R, W LAND ET AL 2,387,800

ACTUATOR Filed July 19, 1944 3 sheets-sheet' 2 INVENTORS CHLVIN J. WERNER 61H0 ROBERT W. LELAND BY mem Squwu, MMQQ 51am,

ATTORNEYS OC- 30, 1945 Rfw. LELAND E1- Al.

ACTUATOR DOWN CONTHCTOR 206 lals UP CONTACTOR INVENTORS D N N @J m E. m Ww T I A n v NE m WBV.. ma m c R m v T ?ate`nted Oct. 310, 145

CTUATUR Robert w. Leland Uhio, asslgnors DetroitLMich.,

12 Claims.

This invention relates to improvements in actuating devices and their controls.

It is among the objects of the present invention t provide an actuator move an object or load ated position with a to return the object tion when desired.

A further object of the present invention is to provide an actuator which is adapted to move an object or load from its normal position into its operated position in a minimum time after control mechanism has been operated to set the actuator in motion. f

The actuator of the present invention is particularly adapted to operate the bomb-bay doors of a warplane in which it is of great importance to assure quick opening of the doors substantially immediately upon the operation of a control mechanism within reach of the operator.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 is a part sectional view of the actuator its normal retracted or door closing position. Fig. 2 is a fragmentary view of the actuator shown in Fig. 1, parts, however, being shown in the extended or door opening position,

Fig. 3 is a fragmentary view of a warplane havingits bomb-bay doors equipped with the present invention.

Fig. 4 is a wiring diagram schematically showing the various control devices and their electrical connections and circuits.

Fig. 5 is a portion of the wiring diagram shown in Fig. 4 illustrating the switch operating cam in the position in which it has reached its lowermost door actuating lever.

Fig. 6 is a similar view showing the switch operating cam in the position in which it will be when the motor reaches its which the door operating lever is in the door quick movement, and then or load to its normal positravel to release the Vclosing position.

Referring to the drawings and particularly to the Figs. 1 and 2 thereof, the actuator is shown comprising an electric motor 20 having an apertured lug 2| at its one end which forms which the actuator is the plane, as shown in particularly adapted tol from normal into operwill be when the nutand Calvin J. Werner,

yton, to General Motors Corporation, a corporation of Delaware Application `luly 19, 1944, Serial No. 545,715

uppermost position in the motor is seated upon and secured to a gear housing 22 in any suitable manner. 'Ihis electric motor 20 is of the type shown in the copending application of Calvin J. Werner, Serial No. 468,475, led December 10, 1942 and comprises an armature having a shaft to which a driving disc is attached. An electromagnetic clutch as illustrated and described in the above mentioned copending application is also provided in this device, said clutch being adapted to be with the energization of the electric motor 20 for purposes of connecting the stub shaft 23 with the electric motor so 'that it may be rotated thereby. The one end of this stub shaft is journalled in a ball bearing in the motor housingas illustrated and described in said copending application, the opposite end of said stub shaft being supported by a ball bearing 24 nested in a recess provided at the inner end of the tubular screw shaft 25.

In the housing 22 there are provided two ball bearings 26 and 21 which rotatably support the annular gear 28 secured to the inner end of the screw shaft by being threaded thereon and having locking pins 29 passing through the gear and screw shaft. The housing 22 contains two ball bearings 30 and 3l which rotatably support an annular gear 32 having outer peripheral gear teeth 33 at its one end and inner peripheral gear teeth 34 adjacent its other or bottom end. A

worm pinion 35, secured upon a shaft journalledi in the housing 22, meshes with the outer peripheral gear teeth 33 of the annular gear 32, holding said annular gear against rotation when the electric motor 20 is operated to rotate the screw shaft 25. The shaft of worm pinion 35 is adapted to be rotated manually to rotate the screw shaft 25 independently of the motor 20. This feature is thoroughly illustrated, described and claimed in the copending application of Calvin,l J. `\Werner, Serial No. 536,913, filed May 23, 1944.

The stub shaft 23 has an eccentric portion 20 upon which two roller bearings al andy 42 are supported. These roller bearings in turn support` the epicyclic gear member 43, one portion having external gear teeth 42 adapted to mesh with the internal gear teeth 36 'of the annular gear 32,v another portion of the epicyclic gear 43 having external gear teeth 45 meshing with the internal gear teeth 46 of the annular gear 28 which, as has previously been described, is positively se,- cured to the inner end of the screw shaft 25.

From the foregoing it may be seen that, when the electromagnetic clutch, not shown, is energized with the energization of the electric motor energized present instance.

epicyclic gear at a reduced rate and, in rotating,V

it will transmit rotation to the' annular gear 28, with which a portion of said epicyclic gear is also in operative connection, thereby resultingtin a rotation of the screw shaft 25 at a reduced rate.V

The above described portion'of the present ac-4 i tuator is similar to the construction shown inthe above identified copending applications. The new features of the present invention willnow be described.

At the bottom or free end of the screw shaftA 25 there is secured a ball bearing member; 50 having inner and outer races. The screw shaft has a helical, annular outer groove 5| throughout its length. A nut 52 ts about the screw shaft 25, the inner annular surface of the nut being provided with a helical annular -groove coincidental in pitch'and size with thehelical annular groove on the screw shaft 5|. The grooves of the shaft and nut coinciding, form a helical channel in which traveling balls 53 are provided, mechanicallyv connecting the .nut with the screw shaft. Details of construction of this type of mechanical connection between a nut and a screw shaft are fully set forth in the copending application of Calvin J. Werner, Serial No. 468.475 previously referred to, and therefore no detailed description will be given 'in the Suffice vto say that the Vtraveling balls 53 in the helical groove between the nut and shaft provide mechanism connecting the nut to the shaft in a manner similar to anv ordinary screw thread, the ballconnection, in

lieu of the ordinary thread however, reducing friction to a minimum.

An actuating member or shifter 60 inthe'form of a tubular member has its'inner end secured to a collar 6|, the outer or opposite vend of said I tubular member' 60 having the anchoring member 82 secured thereto by screws 63. vThis anchoring member 82 has a recess 84 vfor receiving the attachment lug 85, Fig. 3,fforming a portion o'f a plate 66 which is attached to the bomb-bay door 61 of the warplane 68. The anchoring member 62 has a projection 69 extending upwardly into the tubularmember 88, the inner end of the projection :69 lying adjacent to a flange 10 on the nut 52 whensaid nut and 'the member 60 are on normal positidn. A latch 1| hingedly is secured to member 62, spring'12 urging said latch into locking engagement with the 'outer race member of the ball bearing 50 when the tubular member 60 is.in normal yposition 'as shown in Fig. 1. I'he nut 52 has a tapered end portion 13 which is in almost touching proximity to the' latch 1| when the nut and latch are innormal position.

A collar 15 is'securely fastened to the tubular member 60 in any suitable' manner as forinstance by welding, screws 16 securing a tubular guide member 11 to the collar 15. In the annular space provided between the tubular mem; ber 11 and the tubular member 60 there is a heavy duty coil springs 18, one end of' which rests upon the collar 15, the other end abutting against .the clamping collar 19 which is threadedly secured in the lower, outer end of the gear housing 22 and also acts to maintain the bearings 21A` and 26 with their internal annular gear 28 supported in proper. position inthe gear housing. Alin the normal position as shownin Fig. 1, the heavy duty spring 18 exerts a constantforce upon the collar 15 to .urge the member 68' outwardly.

' However; this isnormally prevented due to the `fact that the latch 1| on the attachment mei-n ber 82of the `member-6|) lockingly engages the vouter race `ofba1l :bearing 50 carriedat the lower endof the screw shaft25.

AAdust cover tube 8| has its one end anchored to the clamping ring 19 by means .of screw 82,

f the other end of said tubulardust cover 8| having an inner annular sealing ring 88 which wipingly engages the tubular member 11. A

Fig. 3 is a fragmentary view of a battle plane fuselage having bomb-bay doors 61 and hingedly attached to the fuselage and adapted tobe closed by the device of the present inven-v tion. When approaching a target the operator opens ythe bomb-bay doors 61 and |61, after which the bombardier releases the bomb illustrated at |68 at the proper moment. In order that a minimum time be consumed between the opening of the bomb-baydoors and the release of the. bombs, it is desirable thatthe bomb-bay doors open quickly, for to open the bombf-bay doors slowly or a considerable time before thev bombs are released would offer appreciable re-- sistance-.and affect the .speed .and flight of the plane.

Whenthe operator desires to open the bombbay doors, controlmechanism is actuated whereby the electric motor 20 andthe electromagnetic clutch associated therewith are energized, rendering both active and thereby causingthe motor 2liv to rotate the screw shaft 25 in such a direc-` tion that the nut 52 thereon will be moved longitudinally downwardlyor -towardthe free end of the-screw shaft. inasmuch as the tapered end 18 of the nut normally engages the `latch 11| which holds the door operating lever 80 in normal doorclosing position,.only a very slight movement of the -nut 52fis necessary to move the1latch-1I out ofV engagement with the outer ,race` of the ball bearing 58 and therebyjelease, the member 6 0*` I attached towhe bomb-bay door. As soonas the eratedor door opening position as shown in Fig. 2. When the actuator is in the position shownlatch 10 is movedffrom locking engagement with the -ba1l.race, the heavy `duty spring 18\becomes effective quickly to move'the member 80 from its normal position as yshown in Fig. l, into .its opin Fig. 2, the bomb-bay doors are wide openv as shown in Fig. 3 and the bombardier may then release the bomb |68. When the bombing operation is completed the operator again closes the bomb-bay doors 81 and |61- V by moving'a control device to the up position in whichcircuits are completed, causing the electric motor 20 to rotate.

in a direction opposite to that in which it was rotated to open the doors. Now the screw shaft 25 is rotated in the opposite direction and the nut 52' starts to move upwardly on the screw shaft 25. In' its dooropening position the ring 6 |v on the upper end of the door operating tubular member 60 normally rests upon the upper flange |52 .of the nut as shown in Fig. 2; therefore as the nut 52 moves'upwardiy `this member 60 is drawn upwardly-'toward the gear housing v22,thus caus ing the bomb-bay-doors 61 and |61 to be closed.

When the member 60 has been moved to full doorclosingposition, itsV latch .1| will again engage the outer race of ball bearing v5|! toglock'the lever in this door closing position. As 'soonas the nut has reached rthe positionin which'themember the screw shaft 25 will cause the nut 52 to movel g downwardly. When the nut 52 reaches the normal position as shown in 1, in which the tapered end '|3 thereof merely engages the latch 1|, another automatic means willbecome effective to break the` motor connections and stop its operation.

Immediately after the nut has been moved to its uppermost position in which the member 60 is in its full door closing position, the motor might be stopped and permitted so to remain until it is desired to again open the doors, at which time the circuit could be completed with the motor to causeits rotation and consequent rotation of the screw shaft 25 so the nut will move downwardly toward the latch 1| and upon engaging and operating said latch 1| the member 50 could lbe re-` leased to render the heavy duty spring 'i8 operative quickly to move the lever to open the bombbay doors. However, with such an arrangement considerable time would be consumed in the travel of the nut from its extreme upper position to the lowermost position in which the latch is released. In order to eliminate this undesirable interval of time, which might appreciably affect eicient bombing and in order to obtain immediate opening of the bomb-bay doors upon actuation of the proper control mechanism, applicants have so arranged their control devices that the motor operation is reversed when the nut reaches its uppermost position and is not stopped until the nut reaches its normal position where it merely engages latch 1|, but does not release it.

member 60 by the flange 10, such sticking of the doors in their closed position could be readily overcome. v,

In order to provide automatic controls as referred to above whereby the motor 20 is caused to rotate in one direction only suiciently to rotate screw shaft 25`so that the nut 52 moves downwardly to release latch 1| and then stop, following which control devices may be actuated to cause the motor to rotate in the opposite direction suiciently to move the nut 52 so that member 60 is again returned to its full door closing position and so latched and then to cause a reversal of the motor automatically hereby the nut 52 is again returned to its normal position as shown in Fig. 1 and the motor operation stopped, applicants have provided an automatic circuit making and breaking device driven from the speed reducing gearing to provide properly timed control.

The annular gear 28 of the speed reducing gearing has an outwardly extending ange on the outer peripheral surface of which is provided a low pitch worm tooth of approximately one and a half to two convolutions about the flange. This worm tooth engages a pinion |0| secured to a faasasoo shaft\|02 which is Journalled in the gear housing 22 so as to be substantially tangential to the annular gear 28. Speed reducing gearing including a series of gears |03, |06, |05, |06 and |01 connect a shaft |08 operatively with the annular gear 28 ofthe speed reducing gearing of the actuator. Shaft |08 operates a lswitch control cam |09. This switch control cam is adapted to actuate the movable contacts of the circuit control switches ||0, ||I andIkIZ, which will be dennedly described in connection with the circuit diagram for Figs. 4, 5 and 6. Illustrations of these control devices in Figs. 4, 5 and 6 are merelydiagram'matc and may be-\ of any suitable proper time in its rotation certain switches will v to actuate the solenoid core 2|`| to lift the bridg-1 be opened and others closed to control motor operation.

The control device includes aselector switch 202 having a movable contact arm 203 adapted to be moved into electrical engagement with the terminal 204 which may be termed the up terminal and also moved in the opposite direction into electrical engagement with the terminal 205 which -may be called the downf terminal.

Two electromagnetic contactors are provided, the one designated by the numeral 206 being termed the down contactor and comprises an electromagnetic winding 201 adapted, when energized, tovactuate a solenoid core 208 upon which `are carried two bridging elements 209 and 2|0. Bridging element 209 is adapted to connect the two terminals `2 and 2| 2, while bridging element 2|0 is adapted to connect terminals 2|3 and '2M of this contactor. The fup contactor designated by the numeral 2`|5 comprises an electromagnetic winding 2|6 adapted, when energized,

ing element 2|0 into bridging engagement with the terminals 2|9 and v220. A lock-out relay 225* is provided, comprising an electromagnetic wind, ing 226, adapted, whenenergized, to attract thel solenoid core 22,1 and move it upwardly to break the normally engaging 4contacts 228 and 229 of` the relay and then atthe same time to cause engagement of the normally open contacts 230 and 23| of this relay.

The source of power for operating the actuator is` a storage battery 235 grounded at its 011 side and having its other side connected to a terminal 236 of the master switch 231 Whose other terminal 238 is connected with the movable contact arm 203 of the selector switch 202.- The reversible motor has two field windings 240 and 20|, each of which. when energized, causing the 'relectric motor to operate in a respective direction When it is energized. The electromagnet clutch previousl'ymentibned comprises an electromagnet winding 250 which, when energized, will energize the driving disc 25| operatively connected with the shaftof the motor armature so that it may attract the movable armature 252 which isop- ,eratively connected with the stub `shaft 23 of the .speed reducing gearing. When the 4motor and therefore the driving disc`25| of the motor is not energized, the armature 252 is held in frictional lthe lolectromagnet clutch are not energized ands..l

be described. Normally the bomb-bay doors 61 and |61 areV closed so that they will conform to the contour f the body of the plane fuselage.

When it is desired to'open the door preparatory to releasing bombs |66, the operator at any time previously thereto has closed .the master switch 231 which connects the storage battery or power source 235 withthe selector switch 202. To open the doors, the operator moves the movable contact member 203 clockwise into engagement with the stationary terminal 205 of said switch, thereby completing the following circuit: from the battery across the terminals 236 and 236 of switch 231 through the movable contact 203 of selector switch 202 to the terminal 205 thence through wire 260 to the juncture point 26| from whence the currentwill flow throughthe wire 262, the movable contact I I3 across the two contacts 263 of the switch H0, the contacts 264 of said switch being open `due to the fact that the rubber block of the movable contact arm 3 is riding upon a high spot of the cam |09 which is now immovable. From switch contacts 263 the current flows through the wire 265 through the electromagnet winding 201 of the down contactor 206 thence back to the source of power via the ground connections. Energization of the electromagnet winding 201 will cause the solenoid core 206 thereof to be moved upwardly, shifting the bridging elements 209 and 2|0 into bridging engagement with their respective stationary terminals, thereby closing the following circuits: from th source of power 235 across the switch 231 to the juncture point 266 thence to the ter.. minnal 2||, bridging element 206, terminal 2I2 through wire 261 to the juncture point 266 thence through the motor field 24|',wire 269 to terminal 2|3 of the down contactor, thence acrossI its e i bridging member 2|0 to the'terminal 2|4 and back to the source of power via the ground connections. A portion of this current flow will leave the juncture-266, flow through the wire 210 to the juncture 21| from whence a divided circuit is established, one through the armature windings of the motor to ground, the other through the electromagnet clutch winding 250 to ground. With all of Vthese circuits completed, the electro-pA magnet clutch is energized to move the armature 252 into operative engagement with the motor driving disc 25| which is now being rotated in one direction due to the energization of the motor field 24| and armature circuits. This rotation of the motor is such as to cause rotation of the screw shaft 25 to move the nut 52 thereon downwardly so that its bevel end-13 actuates the lockink latch 1| out of locking engagement with the outer race of the ball bearing thereby releasing the door operating member and permitting the heavy duty spring 16 to be active quickly to shift the bomb-bay doors widely open.

As the electric motor and consequently the speed reducing gearing and the screw shaft 25 are rotated to move the nut downwardly, the gear 26 of the speed reducing gearing is actuating switch operating cam |09 in a clockwise direction through the timing gear connnections. As soon that is opposite to the direction it rotates in reas the nut 52 is moved downwardly to release the s door operating member latch 1| and thereby renderv the spring 16 effective, the cam |06 will` have vreached a position in which the rubbing block on the movable contactarm` I I3 of switch ||0 enters into the. recess 200 of cam |09, thereby permitting thescontacts` 263 of this switch to -be separated and the contacts 264 of this switch to be engaged. Separation of contacts 263 breaks the .circuit through the electromagnet winding 201 of the down contacter 206, thereby deener- -gizing the contactor and causing it to drop to circuit breaking position in which the bridging ele#- ments 209 and 2|0 are moved out of engagement with their respective stationary terminals and consequently break the motor circuits and stop its operation. The closing of contacts 264 will render a circuit including a light 212 active as Asoon as switch 213 is closed by the bomb-bay y doors reaching their wide open position. 'I'hus when the bomb-bay doors are widely" open, the light 212, visible to the operator will indicate that the bomb-bay doors are wide open and that bombs may be released.,l The positions ofswitches f ||0, and ||2 under these circumstances are clearly illustrated in the Fig. 5. Switches and ||2 are inactive' electrically during this phase of/the actuator operation.k y

As soon as the dropping of the bombs has been completed and the operator/desires to again close the bomb-bay doors 61 and |61,he will actuate the movable contact 203 of the selector switch 202 counterclockwise so that said movable contact 203 is disengaged from terminal 205l and moved into electrical engagement with terminal Now the following circuits are completed: from the source of electrical power 235 across the terminals-236 and 238 of switch 231 to the movable contact arm or member 203 of the selector switch through terminal 204, wire 300 to the juncture point 30|, thence through wire 302 to the movable contact arm |||a of the switch across its now closed contacts 303 through wire 304 thence across the engaging contacts 229 and 226 of the relay 225, through wire 305, electromagnet winding 2|6 of the up contacter 215 back to the source of power via the ground connections. 'Energizatlon of the electromagnet winding 2|6 will cause the raising of the solenoid core 2|1 and its bridging element 2|6 whereby contacts 220 and 2|9 are connected together to establish the following circuit: from the source of power 235 across switch 231 to the juncture point 306, thence from terminal 220 to terminal 2|9 via the bridging element 2|6, wire 301, motor field 240 to the juncture .306 thence to the juncture21| where a divided circuit through the armature and through theelectromagnet 250 back to the battery via ground connections will be established.

With these motor connections completed', the motor 20 will now rotate in an opposite direction,

sponse to the closing of the down contactor 206. As the motor rotates in this opposite direction, its connection with the screw shaft 25 through the electromagnetic clutch and speed reducing gearing previously mentioned will rotate said screw shaft so that the nut 52 will be moved upwardly toward the upper inner end of the screw shaft.

When the doors are opened, the actuator parts assume relative positions as shown in Fig. 2, that is, the ring 6| of the door operating member 60 aseaeoo rests upon the flange |62 of the nut 62. Now as ,the nut is moved upwardly in response to reverse operation of the screw shaft 25, it will carry with it the door operating tubular member 60 whereby moving the door attached thereto into its closed position, this position being reached when the nut 52 has moved the lever so that the latch 1I again lockingly engages the outer race of the ball bearing 50, as shown in Fig. 1. As the motor speed reducing gearing and screw shaft 25 rotate in this reverse direction, the gear 28 of the speed reducing gearing will, through the timing gears shown in Fig. 4, actuate the switch operating timer |09 counterclockwise so that the rubbing block on movable arm I I3 of switch 0 will leave the recess 200 and again ride the high surface of cam I 09, thus again opening contacts 260 of switch I I and closing its contacts 263. At the same time the rubber block on the movable contact arm 2a of the switch ||2 will ride the high portion of the cam so that the normally open contacts 306 thereof will be closed and the normally closed contacts 301 ofswitch II2 will be opened. As soon as the nut 52 reaches its uppermost position on the 'screw shaft, in which posi- -tion the door actuating tubular member 60 is again latched in door closing position, the cam |08 will have been moved to assume the position as shown in Fig. 6 where the recess 20| thereof will lie adjacent the rubbing block of the movable contact arm IIa of the switch III. Now this rubbing block will enter the recess 20|, permitting the movable contact arm III a to move to open the contacts 303 of switch and to close the contacts 308 thereof as shown in Fig. 6.

Separation of contacts 303 breaks the circuit flowing across contacts 228 and 229 of the relay 225 and consequently the circuit through wire 305 and the up contact Winding 2|6, thereby deenergizing the up contactor and permitting it to fall into circuit-breaking position in which contactors 2|9 and 220 thereof are disconnected one from the other, thereby breaking the motor circuit to stop motor operation. Now the motor ceases to operate in this reverse direction, however, With the closing of contacts 308 of the switch and the closing of contacts 306 of switch I|2 due to the position of the cam |09 as shown in Fig. 6, which is the position of said cam ,when the motor ceases its reverse direction, the following circuits will be established: from the source of current 235 across switch 231 to the movable contact arm 203 of the selector switch 202, thence through terminal 20B still engaged by said arm 203 through wire 300 to the juncture point 30|, thence through wire 302 across the now engaging contacts 308 of switch through wire 309 to the movable contact arm II2a of the switch |I2 across the now closed contacts 306 of said switch |I2, thence through the wire 260 to the juncture point 26|, thence thru the Wire 262, contact arm |I3 of the switch' |I0 across the now closed contacts 263 of the switch I I0, wire 265, electromagnet winding 201 of the down contactor 206 back to the source of current via the ground connections. Energization of the down contactor winding 201 will effect actuation of the contactor to bridge its stationary contacts 2|| 2|2 and 2I3-2I6 Via the bridging elements 209 and 2| 0 respectively thereby again establishing the motor circuit so that the motor will operate in its original direction, that is in a direction to actuate the screw shaft 25 so that the nut 52 thereon moves downwardly. It will be seen that this is 'automatic and requires no operation of any device by the operator after he once has actuated the selector switch into the up position initially to move the nut from its lowermost position as shown in Fig. 2 to the uppermost position in which ithas just moved the door operating member 60 into full door closing position.

At the same time, closing of contacts 308 of the switch ||I completes a circuit from the juncture point 30| through wire 302 across contacts 308 through wire 309 thence through wire 3I0 to juncture point 3|| thence through the electromagnet winding 226 of the lock-out relay 225, energization of winding 226 will cause the solenoid core 221 thereof to be`moved upwardly to break contacts 228 and 229 and engage contacts 230 and 23|. With the closing of contacts 230 and 23| current can then ow from the source across the switch 231, selector switch contact 203, termina1204, through wire 300 thence across contacts 230-23| to juncture point 3| I and thence across the magnet winding 226 thereby holding said relay in a position to maintain the contacts 230 and A23| in circuit with the up contactor winding 2| 6 open.

As the motor speed reducing gearing and screw shaft 25 rotate to move the nut 52 downwardly and to rotate the switch operating cam I 09 clockwise, said cam |09 will eventually reach its original position as shown in Fig. 4. However before the extreme down position of the nut is reached, or shortly after the motor starts on its directional rotation to move the nut downwardly, contacts 308 of switch l will again be broken and contacts 303 thereof be engaged. With the breaking of contacts 308, the original circuit across them and through the lock-out relay winding is broken, however, the other circuit through this winding 226 is maintained due to the fact that contacts 230 and 23| are held closed and a circuit across them and through the lockout relay winding 226 is maintained. Therefore the circuit across the contacts 306 of switch II2 and contacts 263 of switch H0 to the down contacto;` winding 201 is maintained to permit the motor circuits to be retained for purposes of continued motor operation to move the nut downwardly.

When the nut reaches its normal position as shown in Fig. 1, in which its bevel edge 13 merely engages the latch 1 I, the cam |09 will have been operated into the position as shown in Fig. 4 so that contacts 306 of switch II2 are disengaged. With the separation of these contacts 306 the circuit including contacts 263 of switch I|0 and the winding 201 of down contactor 206 are concurrently broken and-therefore the contactor 206 is deenergized to permit it to drop to circuitbreaking position, thereby breaking the motor circuit and stopping motor operation in this direction. Now all A'elements of the actuator and its control mechanism with the exception of the selector switch contact arm 203 are in their normay position as contact 203 may still be kept in engagement with the terminal 204 to complete the following circuit Without effecting movement of any element of the device: from the battery across switch 231, selectorswitch arm 203 and its terminal 204, wire 300, contacts 230-23| through the magnet Winding 226 of the lockout relay 225 to maintain contactors 230 and 23| closed, also from contacts 230-23|, juncture point 3II through the wire 3I0, across contacts 301 of switch II2 thence through the indicator light 6 Sil and across contacts BIB, which are maintained closed when the bomb-bay doors are closed, thus indicating to the operator that the actuator has closed the bomb-bay doors. `When the oper- -the system ceases operation. The control mechanism is then operated to close the doors, the motor actuating the screw to'move the nut up-l wardly Vfor purposes of pulling the doors into closed position, then the control mechanism acts automatically to cause reversal of the motor for purposes of returning thenut downwardly into its normal position. Downward movement will be stopped when the nut reaches its normal position and before it has moved beyond its normal position in which it will again release the doors to permit their being opened by the heavy-duty spring which actually provides the power for opening the doors.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, ail coming within the scope of the claims which follow.

What is claimed is asfollows:

1. In a device of the character described, the combination with a closure member adapted to be moved from closing into open position with a quick action; a spring loaded shifter connected to the closure member and operative to actuate said member; a latch engaging said shifter and releasably holding it in spring loaded position in' which the closure member is maintained in closing position; a screw shaft vwith anon-rotatable nut threaded thereon and movable axially thereon in response to rotation thereof; means on said nut being operative, in response to axial movement on the nut in one direction; on the screw shaft, rst to engage the latch `and'release said shifter and second to strike saidshifter and start it on its springy actuated movement completely to move the closure member to 'full open position, other means on said nut. operative in response to axial movement of the nut in the opposite direction on the shaft directly to engage the shifter\ and return it into normal spring loaded and latched position; and means for rotating Ythe screw shaft in` either direction. 1

2. In a device of the character described, the combination with a load adapted to be moved between two positions; a screw shaft; a nut threadedly carried by said screw shaft; a spring loaded member carrying the load; a detent on the screw shaft; a latch on the spring loaded member, operative to engage the detent and lock said member in normal, spring loaded position; means on said member engaging the nut Ato prevent its rotation but permitting relative longitudinal movement on the screw shaft; means for turning the screw shaftV in either direction to effect'longitudinal movement of thenut on the screw shaft; means on the nut operative as it-.moves in o`ne direction, toy engage the latch and release the spring loaded member for quickly shifting the assasoo load into fully operated position: means Ron the;` nut, operative as said nut moves in the opposite vent rotation of the nut; a latch on the tubular 'Y member, engaging the screw shaft and releasably Y holding the member in door closing position; a

coil spring engaging the member and exerting a constant force thereupon to urge it toward the door opening position; and means for rotating the screw shaft, in one direction to cause the nut to move into engagement with the latch to release the tubular member whereby said spring may actuate it to open the door, and in the other direction to. cause the nut to engage and move said member to compress the spring, actuate the door into its closed position and again establish engagement of the latch with the screw shaft.

4. In a device of the character described, the combination with a load adapted to be moved between normal and operated positions, of a spring loaded shifter attached to the load and latched in normal position; a screw shaft threadedly supporting a nut; means on the shifter engaging the nut to prevent itsrrotation but permitting longitudinal movement thereof, said nut, when moving in one direction, being operative to unlatch and release the shifter to permit it to move the load quickly from normal to completely operated position, and operative when moved in the Opposite direction directly to engage and move said shifter to lift the load and return it to its normal position; and means for turning the screwl shaft to effect longitudinal movement of the nut in either direction.

5. In a device of the character described, the combination with .a door adapted to be moved from closing into open position with a quick action, of a spring loaded shifter adapted to actuate v said door into open position; a latch normally holding said shifter in door closing position; a screw shaft having a nut threadedly mounted thereon said nut being held against rotation and being movable longitudinally on said screw shaft by rotation of the shaft; a reversible electric motor; means for connecting the electric motor with the screw shaft to rotate it in either direction, whereby the nut ismoved first to engage the latch and release the spring loaded shifter to move the door into open position in response to rotation of the screw shaft in one direction and second to .engage and actuate the `shifter to lift the door into its closing position; and control means for effecting operatic of the electric motor in either direction.

6. A device in accordance with claim 5 in which,

- however, the nut, is normally located on the screw shaft in close proximity to the latch which holds the shifter in door closing position whereby only several turns of the screw shaft are required to move the nut to engage the latch and release the shifter; selective control imeans adapted to be actuated to effect rotation f the electric mo- Y tor in one direction or the other; and automatic vcontrol means for reversing the operation of the electric motor after it has actuated the screw shaft to move the nut into a position in which the shifter has closed the door and for stopping this reversed motor rotation when the nut has reached its normal location on the screw shaft.

7. In a device of the character described, the combination with a normally closed door; a spring loaded tube for operating the door; a latch holding the tube in door closing position; a screw shaft; a nut threadedly carried by the screw shaft and normally engaging the latch; means connecting the nut to the tube to permit relative longitudinal movement therebetween but preventing rotation of the nut; a reversible electric motor adapted to drive the screw shaft in one direction to actuate the latch to release the tube and to strike said lever to start it on its door opening movement, said motor being adapted to drive the screw shaft'in the opposite direction whereby the nut will engage and move the lever into its latched, door closing position; and means for controlling operation of the electric motor.

8. A device in accordance with claim 7 in which, however, there is provided control mechanism including a selector switch adapted to.be operated into one position to effect operation of the motor to rotate the screw shaft so that the nut thereon moves to engage the latch and release the spring loaded tube; a circuit breaker adapted to stop lmotor operation when the latch is released; timer means driven by the motor to actuate said circuit breaker; control devices rendered effective by the operation of the selector to another position to eect operation of the electric motor to rotate the shaft so that the nut thereon moves to shift the tube into its normal latched, door closing position; means for reversing the rotation of the electric motor when the tube is moved into its latched position; and means for stopping the motor when the nut reaches its normal, latch engaging position, said reversing means being automatically controlled by the motor driven timer means.

9. In a device of the character described, the

combination with a normally closed door; of a spring loaded tubular member for operating said door; a latch normally holding the member in the door closing position; a screw shaft; a nut threaded to said screw shaft and normally engaging the latch; means on the tubular member for preventing rotation of the nut but permitting relative longitudinal movement between the nut and the member and screw shaft; a reversible electric motor; speed reducing gearing for connecting the electric motor with the screw shaft control mechanism for effecting operation of the electric motor in one direction to rotate the screw shaft for moving the nut to actuate the latch and release the spring loaded member to open the door, and for effecting operation of the electric motor in the other direction for moving the nut to engage and actuate the member into its normally latched, door closing position; a control device for stopping motor operation when the nut has released the member to open the door; a second control device for reversing motor operation when the nut has returned the member to its normal door closing position; a third grontrol device for stopping motor operation when the nut is moved into its normal latch engaging position; and a common means, driven by the speed reducing gearing for actuating said three mentioned control devices in proper time and sequene.

10. In a device of the character described, the combination with a normally closed door; of a spring loaded tubular actuator for operating said door; a latch normally holding the actuator in the door closing` position; a screw shaft; a nut threaded to said screw shaft and normally engaging the latch; means on the actuator for preventing rotation of the nut but permitting'relative longitudinal movement between the nut and the' actuator and screw shaft; a reversible .electicv motor; speed reducing gearing for connecting the electric motor with the screw shaft; control mechanism for effecting operation of the electric motor in one direction to rotate the screw shaft in the other direction for moving the nut to engage and move the actuator into its normally latched, door closing position; a `control device for stopping motor operation when the nut has released the actuator to open the door; a second control device for reversing motor operation when the nut has returned the -actuator to its normal door closing position; a third control device for stopping motor operation when the nut is moved into its normal latch engaging position; a single cam for operating the said, last mentioned three control devices in proper time and sequence; and driving connections between Ithe cam and speed reducing gearing.

11. A unitary device for moving a load between normal and operated positions, comprising in combination, a shifter attached to the load; a detent engaging the shifter to lock it in the normal position; a spring engaging the shifter and urging it toward the operated position; a prime mover capable of .reverse rotation; a screw shaft rotated by said prime mover; a non-rotatable nut threaded to said screw shaft and movable axially thereon, in response to rotation of the shaft inv one direction, to engage and actuate the detent to release the shifter whereby the spring quickly thrusts the shifter and'its load into fully operated position, said nut moving axially on the screw shaft in response to reverse rotation thereof, directly to engage and return the shifter and its load into detent engaging, normal position.

12. In combination with a, reversible prime mover, of a screw shaft driven thereby, a nonrotatable nut threadedly secured to the screw shaft and movable axially thereon in response to rotation thereof; a load carrying shifter; a spring urging the shifter into one position; means on the shifter engageable by the nut for moving the shifter into a second position and compressing the spring as said nut moves axially on the screw shaft in response to rotation thereof in one direction; a detent engaging the shifter and operative to lock said shifter in its second, spring compressing position; and means on the nut for engaging and actuating the detent completely to release the shifter and render the spring effective to move the shifter fully into its said one position in response to axial movement of the nut on the screw shaft as it rotates in the opposite direction.

ROBERT W. LELAND. CALVIN J. WERNER. 

